My system policies need tending (eg, it won't let me mount a USB drive). BUT the
module in system settings that does this ("Actions Policy") is missing.

I consulted the gentoo wiki, and added dbus, consolekit and policykit use flags
but since I use a desktop profile I assume these were already set. These three
daemons are running, they do a fine job of preventing me from mounting anything.
emerge -DNup world rebuilt nothing relevant.

My system policies need tending (eg, it won't let me mount a USB drive). BUT the
module in system settings that does this ("Actions Policy") is missing.

I consulted the gentoo wiki, and added dbus, consolekit and policykit use flags
but since I use a desktop profile I assume these were already set. These three
daemons are running, they do a fine job of preventing me from mounting anything.
emerge -DNup world rebuilt nothing relevant.

I will not edit xml, period. Human-readable config files are for editing, thanks. You
migrate away from those, you have to provide a working editor.

Thanks to anyone who can help!

You might be looking for the experimental kde-misc/polkit-kde-kcmodules package which modified the system PolicyKit's .xml files directly in /usr
Obviously nothing should be editing /usr and the module was never working properly
Imagine some package modifying anothers static (intended to be non-modifiable) files in /usr, that's quite serious Quality & Assurance violation

They are not. They can write custom JavaScript .rules to /etc or install the polkit-pkla-compat and keep using the XML .pkla format
Both of which has working examples in manpages etc.

This is fucked up.

No desktop has graphical interface for the /etc/polkit-1 files, but you are in luck and this is open source for which anyone can write code for. I bet the KDE developers would be happy if someone wrote something working for http://bugs.kde.org/show_bug.cgi?id=308934

That sad, you don't need to write any .rules for the task you mentioned because ConsoleKit or systemd-logind will tell PolicyKit if the user is local or not and give authorization based on that. This is why it's not a high priority for desktop developers to write such graphical interface since it mostly just works out of box.

It is still pretty messed up that it's necessary to edit some pretty user-unfriendly code
to customize your system. One of the key advantages of linux used to be human readable
configuration files. the minute you go to xml or javascript for configuration, that's over.